Flow elements, in the form of combustion chamber tile elements, consist of the base material that is protected by one or more coatings in order to extend the operating time. The base material of the combustion chamber tile element must in particular be protected from too high a temperature during operation, and therefore the coatings preferably function as thermal insulation. A combustion chamber is usually constructed having two shells. The chamber consists of a sheet metal housing, on the inside of which the combustion chamber tile elements are screwed, which elements thus form a closed combustion chamber. On the surface facing the sheet metal housing, also referred to as the rear face, the combustion chamber tile elements include a plurality of small pins for increasing the surface area. A cooling air mass flow flows between the sheet metal housing and the combustion chamber tile element, which mass flow flows around pins attached to the rear face of the combustion chamber tile element and thus cools the combustion chamber tile element. Surfaces of the combustion chamber tile element that are directly adjacent to the rear face are referred to as edge surfaces. The edge surface that faces in the flow direction of the fuel mixture is referred to as the outlet edge. The rear face and the edge surfaces are typically protected by means of an aluminium-based alitising diffusion coating. A surface of the combustion chamber tile element that faces the actual combustion chamber is protected from the high thermal stresses by means of an APS (atmospheric plasma spray) thermal barrier coating. The APS thermal barrier coating generally consists of an adhesive layer (MCrAlY) and a ceramic consisting of zirconium oxide (ZrO2).
In the case of the combustion chamber tile elements described, the inventors have recognized that in particular two damage mechanisms arise that result in a reduction in the service life of the elements. A first damage mechanism is the corrosion of the outlet edge of the combustion chamber tile element, caused by thermal stresses. In the case of a second damage mechanism, local temperature peaks cause the APS thermal barrier layer on the surface facing the combustion chamber to chip, resulting in planar wear of the base material.
In order to address the above problem, monocrystal base materials are sometimes used today. The inventors have recognized, however, that the disadvantage of this solution is the high outlay for producing the monocyrstals and the associated high production costs.